Surface-active compounds and fuel compositions containing them



SURFACE-ACTIVE COMPOUNDS AND FUEL COMPOSITIONS CONTAINING THEM Richard D. Stayner and Robert A. Stayner, Berkeley, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application December 22, 1951, Serial No. 262,998

14 Claims. (Cl. 52-05) conveniently illustrated by the following structural formula:

Rz-N-RrOSOZ wherein R1, R2 and R3 represent hydrocarbon groups, at least one of which is an arylmethylene group or alkylarylmethylene group having from 1 to 24 carbon atoms in each of the alkyl radicals thereof, the remainder of said hydrocarbon groups being short-chain alkyl groups, and R4 is an alkylene group of from 1 to 7 carbon atoms.

The above compounds are excellent surface-active agents. They are ampholytic in nature and are, therefore, capable of acting either as an acid or a base. The molecule of these surface-active compounds forms within itself a zwitterion between the quaternary nitrogen group and the alkyl sulfate group. Some of the beneficial aspects of both cationic and anionic surface-active agents are thus combined within a single compound to provide a product characterized by distinct and unusual surface-active properties not possessed by either cationic or anionic agents alone.

A further unusual feature of the surface-active com pounds according to this invention is that the quaternary nitrogen group of the ampholyte is more strongly ionizable under certain conditions than an ordinary amino group would be in similar circumstances. For example, under alkaline conditions such as are often encountered in the use of surface-active agents, the compounds of this invention exhibit the characteristics of free zwitterions and may be isolated as such. On the other hand, amino sulfates under alkaline conditions do not possess free zwitterion characteristics.

The new compounds according to this invention may be either preferentially water-soluble or preferentially oilsoluble, depending upon the substituents on the aryl nucleus. A preferred group of compounds is that characterized in having two aryl groups and an alkyl group of from 9 to 18 carbon atoms on each of the aryl groups. Compounds of this latter type are preferentially oil-soluble and are useful in lubricating and fuel oil compositions.

The preferentially oil-soluble compounds which are a particularly desirable species of this invention possess excellent dispersing properties in lubricating and fuel oil compositions. Sludge-forming materials normally present in such compositions and particularly in fuel oils containing substantial amounts of cracked stocks may be maintained in suspension for an indefinite period by these surface-active agents. Undesirable deposition of sludge and the resultant clogging of screens, filters and lines in lubricating and fuel oil systems are thus avoided.

The compounds of this invention, as mentioned in connection with the above structural formula, contain at least one aryl or alkaryl group, each of which is connected by a methylene linkage to the nitrogen. Examples of suitable aryl groups are benzene, naphthalene, anthracene, toluene, xylene, mesitylene, etc., with benzene and tates Patent ice toluene presently preferred for their availability and the high degree of effectiveness characteristic of the compounds containing them. The alkyl substituents of the alkyl aryl methylene groups may be straight-chain or branched-chain in nature and may vary from 1 to 24 carbon atoms in length. The alkyl groups may be derived from various sources such as halogenated hydrocarbons, aliphatic alcohols, and olefins including cracked petroleum fractions, and polymers of ethylene, propylene and butylene. Propylene polymers containing from 9 to 18 and, more specifically, from 12 to 15 carbon atoms per molecule are presently preferred. Their ready availability and unusual chemical stability toward alkylating cataylsts and sulfating agents, derived apparently from their characteristically moderate chain-branching, renders them particularly suitable for present purposes.

The short-chain alkyl substituents on the quaternary nitrogren in the above structural formula also may be straight-chain or branched-chain in nature and may vary from 1 to 7 carbon atoms in length. Alkyl groups containing 1 or 2 carbon atoms are preferred, since they may be conveniently derived from dimethyl sulfate and diethyl sulfate in accordance with the preferred process for pre paring these novel surface-active compounds which is described hereinafter.

The alkylene group, R4, in the above formula likewise may be branchedor straight-chain. It may be obtained by employing any suitable alkanolamine in the preparations hereinafter disclosed. Alkylene groups of from 2 to 4 carbon atoms are preferred since they are obtainable from the ethanol, propanol and butanol amines which are desirable for their effectiveness and ready availability.

The 2-[N,N-di-(alkylbenzyD-N-methyl ammonium]- ethyl sulfates and 2-[N-alkylbenzyl-N,N-dimethyl ammoniumJ-ethyl sulfates which constitute a preferred embodiment of the present invention may be illustrated by the formulae:

m win f iew.

wherein R is a long-chain alkyl group of from 9 to 18 carbon atoms, R is a hydrogen or methyl group and x is an integer of from 1 to 3. These compounds are unusually effective dispersing agents and rust inhibitors in lubricating and fuel oil compositions.

The compounds according to the invention as illustrated by the above preferred class may be conveniently prepared by quaternizing a suitable N,N-di-(alkylbenzyl)- ethanolamine or N-alkylbenzyl ethanolamine with dimethyl sulfate as the first step. The N-alkylbenzyl ethanolamines or N,N-di-(alkylbenzyl)-ethanolamines themselves may be obtained by reacting approximately one or two molar proportions of a long-chain alkylbenzyl chloride having the desired type of alkylbenzyl group with one molar proportion of ethanolamine in the presence of a mild neutralizing agent, such as sodium bicarbonate. The N,N-di-(alkylbenzyl)-N-methyl-N-(2- hydroxyethyl)-ammonium methosulfates or N-alkylbenzyl-N,N-dimethyl-N (2 hydroxyethyl) ammonium methosulfates obtained in the first step may then be reacted with a sulfating agent, such as sulfuric acid or chlorosulfonic acid, to produce the corresponding 2- ['N;N di (alkylbenzyl)=N=methyl ammoniumT-ethyl sul'- fates and 2-[N-alkylbenzyl N,N-dimethyl ammonium]- ethyl sulfates of this invention. As an alternative, the compounds of this invention as illustrated by thepre fcrred species may be prepared by first reacting approxi'-- mately one or two molar proportions of a long-chain.

Example r-Preparation of 2-[N-dodcylbanzylN,N- dimethylammonium]-ethyl sulfate A solution of 150 parts of dodecylbenzyl-chloride,.the dod'ecyl group of which was a propylene tetramer, 49 parts of N,N-dimethyl-aminoethanol and 100 parts ofisopropanoi wasrefluxed for six hours. This solution was cooled; diluted with 200 parts of water and then extracted" with two ISO-part portions of mixed hexane. The; aqueous solution was then concentrated under reduced pressure to yield 173 parts of N-dodecylbenzyl- N,N-dimethyl-N- Z-hydroxyethyl) ammonium chloride in the form ofa viscous, yellow grease. This material, on-analysis, was-foundto contain 3'.47% nitrogen as compared to a theoretical of 3.65%.

1 65" parts of the N-dodecylbcnzyl-N,N-dimethyl-N-(2;- hydroxyethyl)-ammoniumchloride prepared above was dissolved in 100 parts of chloroform and added to a solution of 79 parts of chlorosulfonic acid in 50 parts of chloroform over a period ofabout one hour. The addition-was carried out at. a temperature of 23-27 C. After theaddition was complete, the reaction mixture was stirred at about 25 C; for two; hours andthen poured onto 100 parts of ice. The water formed was removed and discarded and the chloroform solution was neutralized with sodium hydroxide to a pH of 7.0. It was then washed with two 200 part portions of water and finally concentrated under reduced pressure to yield 86 parts of 2-[N-dodecylbenzyl-N,N dimethyl ammonium]- ethyl sulfate in-v the fornrof a light yellow, tacky, solid material. This material, on analysis, was found to contain 3.23% nitrogen as compared to a theoretical of 3.27% nitrogen.

Example 2.Preparatin of 2-[N,N-di-(d0decylbenzyl- N-methyl ammoniunfl-ethyl sulfate sure to give 50 parts. of N,N,-di-(dodecylbenzyl)-N- methyl-N- Z-hydrox-yethyl) -ammonium methosulfate in the formof a viscous, yellow liquid. This material on analysis gave 1.76% nitrogenas compared with a theoretical of 1.99%. p

30 parts of the; N,N-di- (dodecylbenzyl)-N-methy1:N- (2 hydroxyethyl) ammonium methosulfate. prepared above were dissolved; in 50'parts of chloroform and added portion-wise to l2parts of chlorosulfonic acid in 75 parts of chloroform. The addition was'carried outat a temperature of 13-17 C. After, theaddition was-complete, thereaction mixturowas stirred at' 15- to C. for'one-half" hour and then poured onto-100 parts of-crushed ice. The mixture was neutralized with dilute'caustic solution and then allowed to settle; The aqueous portion was removed and discarded and: the chloroform solution washed with water.

shown by comparison of nitrogen and sulfur, analysis withtheoretical tobe 2-EN;N-di:Cdodecy1benzyl)'-N methylammoniuml ethyl sulfate.

Following this, the chloroform so lution was concentratedunderreduced pressure to give parts of a light yellow semi-solid; Thismatcrial was:

Example 3.-Preparati0n of 2-[N,N-di-(n0nylbenzyl)-N- methyl ammoniuml ethyl' sulfate A solution of 19 parts of dimethylsulfate in parts of benzene was added to parts of N,N-di(nonylbenzyl)- aminoethanol in partsof benzene. The nonyl groups on the. benzyl nucleus were derived from propylene trimer. After'the additiomthe solution was refluxed for one hour, cooled to- 30 C. and treated with four parts of sodium hydroxide in 25v parts of water. The reaction mixture was. then refluxed for 20 minutes with stirring, cooled, andthe.water layer removed and discarded. The benzene solution was then washed with two 50 part portions of water andconcentrated under reduced pressure to yield the N,N*di-( nonylbenzyl)-N-rnethyl-N?(2-hydroxyethyl)-ammonium methosulfatc in the form of a light amber colorviscousliquid.

56 parts of the N,N-di-(nonylbenzyl)-N-methyl-N-(2- hydroxyethyl')-ammonium methosulfate prepared above weredissolved in chloroform and added to 21 parts of chlorosulfonicv acid also in, chloroform. The addition was made in increments at a temperature of 1317 C. Aftertheaddition wascomplete, the reaction mixture was stirred at 15-20 C. for one-half hour and poured onto 100 parts of. crushed' ice as in the preceding example. After neutralization with dilute caustic settling and removal: ofthe aqueous portion, the chloroform solution was Washed with water and concentrated under reduced pressure. 32 parts of an amber, tacky solid were thus obtained which was shown by nitrogen and sulfur analysis to be 2-[N,N-di-(nonylbenzyl)-N-methyl ammonium]- ethyl sulfate.

In the above examples, the parts given are on a weight basis unless otherwise'specified.

As mentioned above, the present invention is also concerned with. the preparation of improved hydrocarbon fuelcompositions and,.more particularly, with the preparation: of hydrocarbon fuels having improved properties as burner fuels, diesel engine fuels, and jet fuels.

Inthe. production of hydrocarbon fuels it is desirable economically to. employ considerable quantities of cracked refinery stocks. Such stocks are becoming more and more available due to the ever increasing use of thermal and: catalytic cracking processes in petroleum refinery operations. When employed in burner fuels, diesel-engine fuels, and jet fuels these stocks have the disadvantage. of forming particles: of sludge or gum which tend1todeposit and cause plugging of filters, screens and lines: The necessity for-frequent interruptions of burner, diesel, and jet engine service to replace or unplug clogged filters andscreensconstitutesa serious problem.

Burner, diesel engine, and jet fuel systems ordinarily contain certain amounts of water due to vapor condensation: The. presence of this water tends to. accelerate the formation ofifilterpluggin-g gum and sludge in hydro- V 2+ [N,N-di*(alkylbenzyl) .-N-methyl ammonium] -alkyl sulfates. of '2-[-N alkylbenzyl-N;N-dimethyl ammonium]- alkyl sulfatesd'escribedabove to'norrnally liquid hydrocarbonfuels; any tendency of the fuel to form filter clogging particles of'sludge or gum is substantially overcome; Such hydrocarbonfuel compositions, in addition, have'the: effect of inhibiting rusting. of ferrous metal surfaces withwhich they come in contact, thus substantially eliminating rust-particles that may also lead to clogging of the fuel 5 oil system.

Suitable, hydrocarbon fuel base. stocks for use in the improved-'fuel oil compositions of this invention may be described broadly as petroleum distillates boiling in the range from,about;to-400 C. Such distillates are ordinarily characterizedv byan A. P. I. gravity of at least 20 and usually atleast- 25?. The base stocks may be either straight-run distillates'or cracked distillates. The present invention finds its greatest utility in hydrocarbon fuels of thepreceding types which contain substantial amounts ofcrackcddistillates. With the additives of this. invention such fuels-form appreciable amounts of filter plugging sludge and gum which render them unsuitable for use in operations where. uninterrupted service is desired, as isthe case with mostpresent-day operations.

Very small amounts of the 2-[N,N-di-(alkylbenzyl)- N-methyl-ammoniuml-alkyl sulfates and 2-[N-alkylbenzyl-N,N-dimethyl ammoniuml-alkyl sulfates, in the order of 1% by weight or less, have been found to be entirely effective to prevent line and filter clogging and to inhibit rusting when water is present in the fuel oil system. Amounts in the range of from 0.001 to 0.20% by weight of the total fuel are particularly suitable and proportions in the range of from 0.005 to 0.015% by weight are most preferred in the more specific embodiments of the invention.

In order to facilitate evalution of the improved fuel oil compositions of the present invention and avoid an enormous outlay of time and material, a rapid test method for determining filter plugging characteristics was developed. The results of this test method have been found to correlate well with actual fuel tests using regular fuel oil burners and jet and diesel engines. The test is carried out by mixing 500 ml. of a fuel composition containing 0.01% by weight of the additive with 500 ml. of water containing 102 parts per million hardness calculated as calcium and magnesium carbonates, two-thirds being calcium carbonate. The fuel oil composition and water are shaken in a separatory funnel for 30 seconds, at the end of which they are allowed to stand for minutes. At this point a phase separation occurs and an upper oil layer and a lower water layer are obtained usually separated by a opaque cuff at their interface. This interface cuff is then filtered through a fritted glass crucible with the aid of a vacuum. Only as much oil and water are filtered as are necessary to assure complete extraction of the cuff, usually about 25 ml. However, in cases of severe emulsions the entire contents of the separatory funnel may have to be filtered. The resultant discoloration of the crucible mat by the particles of gum and sludge deposited thereon is used as a comparative measure of the hydrocarbon fuels tendency to plug filters and screens. a

In the comparison the filter is compared with a standard series of 11 filters prepared in a similar manner from fuels of known filter plugging tendency. The standard filters are numbered 0 to 10, the higher numbers being identified with the heavier deposits. For convenience, the rating given a particular test sample is termed its Interface Filter Deposit Rating (IFD) and denotes the number of the filter in the standard series with which it compares in amount of filter deposit.

Table I, which follows, shows the IFD values of a number of fuel oil compositions according to the present invention as compared with a standard fuel of the burner, diesel or jet type. The base fuel employed in each case was a mixture of equal parts of straight-run distillate from a waxy base crude falling in the range of from 196 C. to 357 C. and a Thermofor catalytic cracked fraction boiling in the range of from 191 C. to 297 C.

TABLE I.INTE RFAOE FILTER DEPOSIT RATING IFD Run No.

Additive 2[N,N-dl-(dodeoylbenzyl)-N-methyl ammoni- 0 um]-ethyl sulfate.

2-[N,N-di-(nonylbenzyl)-N-methy1 ammonium} 1 ethyl sulfate.

2-[N-dodecylbenzyl-N,N-dimethyl ammonium]- 0 ethyl sulfate.

None 10 The data in Table I above clearly show the marked superiority of the improved hydrocarbon fuel compositions according to the present invention over a conventional burner, diesel or jet fuel. Runs 1, 2 and 3 each shows that very little or no filter deposit is obtained from fuel oil compositions containing representative 2-[N,N- di-(alkylbenzyl)-N-methyl ammoniuml-ethyl sulfates or 2-[N-alkylbenzyl-N,N-dimethyl ammoniuml-ethyl sulfates of this invention. On the other hand, the fuel oil base stock by itself as shown by run 4 gives an extremely high filter deposit.

The compositions of the present invention were also tested for their rust inhibiting properties. The tests were carried out in accordance with the procedure outlined in ASTM Method D-665-47T. Steel spindles were immersed in an agitated distilled water and fuel oil mixture containing 0.001% by Weight of additive and in an agitated sea water and fuel oil mixture containing 0.005%

by weight of additive. The base stock fuel without additive was tested in a similar fashion. The results of these tests were as follows:

TABLE II.--ANTI-RUST PROPERTIES From the above tests it will be readily observed that the improved fuel oil compositions of this invention possess remarkable rust inhibiting properties as compared with ordinary burner, diesel or jet fuels.

The fuel oil compositions according to the present invention may contain other fuel oil additives in addition to the 2-[N,N-di-(alkylbenzyl)-N-methyl ammonium]- ethyl sulfates and 2-[N-alkylbenzyl-N,N-dimethyl ammoniuml-ethyl sulfates. Such additives include lecithin; oil-soluble alkylaryl polyglycol ethers such as didodecylphenyl dodecaethylene glycol ether; oil-soluble sulfonates such as the lead salts of petroleum sulfonic acid containing from about 20 to 30 carbon atoms per molecule; oil-soluble naphthenates such as the alkali metal and lead salts of petroleum naphthenic acids; alkali metal and lead salts of alkyl phenol disulfide.

We claim: 1. Compounds of the formula:

R1\ R2-I I--R4OSO;

wherein R1, R2 and R3 are hydrocarbon groups, at least one of which is an alkyl aryl methylene group containing from 1 to 24 carbon atoms in the alkyl portion thereof, the remainder of said hydrocarbon groups being shortchain alkyl groups and R4 is an alkylene group of from 1 to 7 carbon atoms.

2. 2-[N,N-di-(alkylbenzyl) N methyl ammonium]- ethyl sulfates having a long-chain alkyl substituent on the benzene nucleus containing from 9 to 18 carbon atoms.

3. 2-[N-alkylbenzyl-N,N-dimethyl ammonium] -ethyl sulfates having a long-chain alkyl substituent on the benzene nucleus containing from 9 to 18 carbon atoms.

4. 2-[N,N-di-(dodecylbenzyl)-N-methyl ammonium]- ethyl sulfate wherein the dodecyl group is a propylene polymer.

5. 2-[N,N-di-(nonylbenzyl)-N-methyl ammonium]- ethyl sulfate wherein the nonyl group is a propylene polymer.

6. 2 [N dodecylbenzyl N,N dimethyl ammoniumJ-ethyl sulfate wherein the dodecyl group is a propylene polymer.

7. A process which comprises refluxing approximately 2 molar proportions of a long-chain alkylbenzyl chloride having from 9 to 18 carbon atoms in the long-chain alkyl portion thereof with approximately 1 molar proportion of ethanolamine in the presence of sodium bicarbonate, quaternizing the di-(alkylbenzyl)-ethanolamine thus obtained with dimethyl sulfate and reacting the quaternary ammonium methosulfate product therefrom with a sulfating agent to give oil-soluble, surface-active 2-[N,N-di-(alkylbenzyl)-N-methyl ammonium]-ethyl sulfates having from 9 to 18 carbon atoms in the long-chain alkyl substituent on the benzene nucleus.

8. A hydrocarbon oil composition containing a small amount suflicient to inhibit line and filter clogging and corrosion of a member of the group consisting of 2-[N,N- di-(alkylbenzyl)-N-methyl ammoniuml-ethyl sulfates and 2-[N-alkylbenzyl-N,N-dimethyl ammoniumJ-ethyl sulfates having a long-chain alkyl substituent of from 9 to 18 carbon atoms on the benzene nucleus.

9. A hydrocarbon fuel oil composition comprising a major proportion of a normally liquid hydrocarbon fuel oil and a small amount sufficient to inhibit lineand filter clogging and corrosion of 2-[NgN df-(alkylbenz/yl N methyl ammoniuml-ethyl sulfates a long-chain alkyl substituent of: from'92to; 1-8;car.bon-; atoms on the benzenenucleus.

10. Av hydrocarbon fuel oil composition comprising a major proportion of a normally liquid hydrocarbon fuel oil and a small amount sufficient to inhibit line and filter clogging and' corrosion of 2-[N-alkylbenzyl-N,N-'dimethyl ammonium-J-ethyl sulfate having a long-chain alky-lsubstituent of from- 9 to- 18- carbonatoms onthe benzene .nucleus 11. A hydrocarbon fuel; oil: composition comprising a major proportion of a normally liquid. hydrocarbon fuel. oil boiling in the range of. fromaboutj 175 C. to about 12. A hydrocarbon fuel oil composition. comprising a. 20

major proportion of a normally liquid hydrocarbon fuel oil. boiling in the range ofifrom about 175* C. toabout 4010 C. andfrom. 0.001 to 0.20% by weight of Z-[N alkylbenzyl NgN dimetliyl ammonium'I-ethyl sulfate having a long cliain-alkylsubstitue'ntof'f1om9 to- 18 carbon atomson the benzenenucleus.

1-3. A hydrocarbon fuel. oil composition as described in clairn= 11, whereinthe normally liquid hydrocarbon fuel 011 contains a substantial" proportion of cracked petroleum distillate 14. A hydrocarbon fuel oil composition as described in claim 12, wherein the'no'rmally-liquid' hydrocarbon fuel oil contains, a-substantialproportion of cracked petroleum distillate.

References Cited iirthe-file ofthis'patent UNITED. STATBES; PATENTS 2,504,977 Gump etfal': Apr. 25;, 1950 

8. A HYDROCABON OIL COMPOSITION CONTAINING A SMALL AMOUNT SUFFICIENT TO INHIBIT LINE AND FILTER CLOGGING AND CORROSION OF A MEMBER OF THE GROUP CONSISTING OF 2-(N,NDI(ALKYLBENZYL)-N-METHYL AMMONIUM)-ETHYL SULFATES AND 2-(N-ALKYLBENZYL-N,N-DIMETHYL AMMONIUM)-ETHYL SULFATES HAVING A LONG-CHAIN ALKYL SUBSTITUENT OF FROM 9 TO 18 CARBON ATOMS ON THE BENZENE NUCLEUS. 